Process for winning copper using carbon monoxide

ABSTRACT

Process of winning copper from chloride containing solutions by treating with carbon monoxide. Process makes copper separable from iron, and can be applied to leach solutions prepared by treating sulfide ores with HCl in the presence of air or oxygen.

United States Patent [191 Dubeck et al.

1 1 PROCESS FOR WINNING COPPER USING CARBON MONOXIDE [75] Inventors:Michael Dubeck, Birmingham; Suk

Joong lm, Southfield. both of Mich.

[73] Assignee: Ethyl Corporation, Richmond. Va. [22] Filed: Oct. 4. 1974[21] Appl. No.: 512,331

Related US. Application Data [63] Conlinuationin-part of Ser. No.267.241. June 28.

1972. Pat. No. 3855.384.

[56] References Cited UNITED STATES PATENTS 924.076 6/1909 Jumziu 75/1171 1 Nov. 11, 1975 924.077 6/1909 Jumuu 75/117 940.292 11/1909 Wells 75/1I 7 X 2.647.825 8/1953 Roberts 75/.. A 3.701.648 10/1972 Ashb et a175/72 3.728.105 4/1973 Skarbo 75/103 3.855.384 12/1974 Dubeck et a1.423/42 Primary Exmniner-G. Ozuki Atwrner. Agent. or FirmDonz11d L.Johnson; Robert A. Linn 57] ABSTRACT Process of winning copper fromchloride containing solutions by treating with carbon monoxide. Processmakes copper separable from iron. and can be applied to leach solutionsprepared by treating sulfide ores with HCI in the presence of air oroxygen.

12 Claims. No Drawings PROCESS FOR WINNING COPPER USING CARBON MONOXIDECROSS-REFERENCE TO RELATED APPLICATION This application is aContinuation-in-Part of copending application Ser. No. 267.241. filedJune 28, I972. now Pat. No. 3,855,384.

BACKGROUND OF THE INVENTION Some copper ores such as bornite andchalcopyrite contain appreciable quantities of iron. For winning copper,it is desirable that the iron be separated. This invention pertains toseparation of iron and copper values and to obtaining highly purifiedcopper metal.

SUMMARY OF THE INVENTION A process for winning copper which comprisesreacting carbon monoxide with source copper values in the presence ofchloride ions.

A process for winning copper from a solution containing a. source coppervalues in the cuprous or cupric ionic state b. iron values. and

c. sufficient chloride ions to bond with substantially all cuprous ionsin said solution; said process comprising contacting said solution withcarbon monoxide, to form a complex of copper chloride and carbonmonoxide, removing the complex of copper chloride and carbon monoxidefrom the solution, decomposing said complex to copper chloride, andreducing the copper chloride to copper metal.

This process can be applied to separation of iron from copper values ina solution prepared by leaching a copper ore of the sulfide type withHCl. the leaching being conducted in the presence of oxygen-containinggas.

DESCRIPTION OF PREFERRED EMBODIMENTS This invention comprises treatingionic copper with carbon monoxide. Although pure or substantially purecarbon monoxide can be used in the process, it is not necessary to doso. The carbon monoxide can be mixed with other gases such as hydrogen,nitrogen, methane. carbon dioxide. or water vapor. Synthetic gases whichare mixtures of carbon monoxide with one of more of these diluent gasescan be employed. Th us, the process can be conducted using producer gas,synthesis gas, water gas, and the like.

In many instances, better results are obtained if substantial amounts ofoxygen are not permitted in the system. In general, the amount of oxygennormally present in any of the synthetic gases mentioned above can beused. Likewise. when conducting the process in a batch fashion in apressure vessel, the liquid ingredients can be added to the vessel openin air, and then the carbon monoxide or carbon monoxide-containing gascan be added. In other words, it is not necessary to remove oxygen by agaseous sweep.

In general, the amount of oxygen should not exceed about 5 weightpercent of the gas phase.

The process is preferentially conducted under carbon monoxide pressure.In other words, although it may be possible in some instances to conductthe process at atmospheric pressure, generally, better results areachieved when super-atmospheric pressures of carbon monoxide are used.Preferably, the carbon monoxide LII pressure is greater than 10 and morepreferably, greater than I00 psia. There is no real upper limit on thecarbon monoxide pressure; and accordingly, the upper limit is restrictedby such secondary considerations as design of the reaction vessel,economics. etc. In general. the process can be conducted at carbonmonoxide pressures up to 5000 or more preferably. 2500 psia. In general.a most preferred carbon monoxide pressure range is from about 200 toabout 1500 psia.

Generally. better results are obtained if the process is conducted attemperatures elevated above ambient. Temperatures within the range offrom about to about 300C. can be used. Higher and lower temperatures canbe used. A preferred range is from about l00 to about 250C.

For the process, better results are achieved when it is conducted usingmetal values in the ionic state and in which an anionic portion of themetal salts consists of chloride ion. It is not necessary for all metalsalts in the starting material to be chlorides. Better results areachieved. however. when there is at least one gram ion of chloride ionpresent per each gram ion or gram atom of copper. The ionic state of thecopper in the starting material is not critical. Thus. one can initiatethe process with cupric or cuprous copper. Of these. cuprous copper ispreferred. Although this invention is not dependent on any theory, it isbelieved use of carbon monoxide will reduce cupric to cuprous copperduring the gaseous treatment.

The resultant copper values obtained by this process generally havelimited solubility in water. The resultant copper values can be in theform of white. lustrous flakes. These are a complex of carbon monoxidewith cuprous chloride. This complex can be removed from the reactionmixture by filtration under pressure to retard its decomposition. ifdesired.

The reaction time is not critical. and it is dependent. at least to someextent. on the other reaction variables employed. In general. times arereduced as temperatures are elevated. In many instances good results areobtained when the carbon monoxide and copper values are allowed to reactfor a period of from about to about 24 hours.

This invention is preferably conducted in the presence of a liquid phaseto facilitate contacting the reactants. The most preferred liquid forthis purpose is water. The pH is not critical and acid or neutralsolutions can be used. The process proceeds well when at least asubstantial portion of the copper values are in solution. Accordingly,the aqueous phase should not be so basic that copper values areprecipitated from solution. The process proceeds very well whenconducted using acidic solutions. Accordingly, it is not necessary toneutralize or partially neutralize any acid leach solution obtained bytreating a copper-containing material. Thus. preferably, one can operateat a pH of from about 1 to about 7, but is not necessary to do so.

Carbon monoxide can be used to separate copper ions from any aqueoussolution. However, this invention is directed, in a primary sense, tocarbon monoxide treatment of source copper values obtained from somesource of copper such as copper ore. copper scrap, and the like. Theores may be oxides or carbonates and may be of the sulfide type. Typicalsulfide copper ores are those selected from the class consisting ofcovellite. enargite. tetrahedrite. tennantite. bornite. chalcopyrite andchalcocite. Of these. bornite and chalcopyrite are 3 preferred.Chalcopyrite is a most preferred copper ore.

The relative amounts of water and source copper values is not critical.Any material from very dilute to concentrated solutions can be used.Likewise, slurries can be employed. In general. the concentration ofcopper is from about O.l grams per liter to about 100 grams per liter.and more preferably. from about 20 to about 80 grams per liter.

The process of this invention is efficaciously employed by usingsolutions of source copper values obtained by leaching a copper ore ofthe above type with HCl in the presence of an oxygen-containing gas. TheHCl may be hydrochloric acid or hydrogen chloride gas. Either of theseagents is used in treating a water slurry of copper mineral concentrateobtained from the above-identified ores. Preferably, this leach processis conducted at about atmospheric pressure and elevated temperature.Preferred temperatures are from about 95 to 105C. The oxygen-containinggas can be pure oxygen. air or a mixture of oxygen and air.

EXAMPLE To illustrate the feasibility of this invention. a test wascarried out to produce the carbon monoxide complex with cuprous chlorideutilizing carbon monoxide and cupric chloride solution. The solutioncontained 58.9 grams per liter copper and 50.6 grams per liter iron.This test solution simulates copper-iron containing solutions availableby treatment with sulfide copper concentrates. Treatment of theabove-identified solution at 170C. using a pressure of carbon monoxideof 445 psia for two hours yielded 60 percent of the copper as thecomplex of carbon monoxide with cuprous chloride. When washed. thismaterial contained about 0.05 Fe.

Similar results are obtained when the process is conducted attemperatures of from about I" to about 250C. and at carbon monoxidepressure of from about lOO to about 1500 psia. Similar results areobtained when the concentration of copper is from about to about 80grams per liter and the concentration of iron is from about to about 80grams per liter. Similar re sults are obtained when the process isconducted at the temperatures and pressures noted from a period of about/2 to about 24 hours. Similar results are obtained at the times,temperatures and pressures noted above when substantially pure carbonmonoxide is employed. or the carbon monoxide is added in producer gas.synthesis gas, or water gas.

The complex of carbon monoxide and cuprous chlo ride produced by theprocess of this invention can be heated to drive off the carbonmonoxide. Then the euprous chloride remaining can be reduced to copperas. for example. with hydrogen.

The above example can be applied. and similar results obtained, totreatment of leach solutions obtained by HG treatment with oxygen of thesulfide ores listed above. Similar results are obtained by treatingsimilar leach solutions made from oxide. carbonate, and silicate oresuch as chrysocolla. malachite, azurite, cuprite and tenorite.

Similar results can be obtained by using the method of the above examplein treating the leach solutions ob tained with HCl and air and an oreconcentrate having the following composition:

A. Principal Minerals Cubanite Cu S.Fe S

4 Chalcopyrite CuFeS Pentlandite (Ni.Fe),,S, Pyrite FeS Pyrrhotite Fe SJ B. Typical Cu and Ni Content Cu to about l27r Ni to about 5% C.Average Assay. One Sample Insolubles 22.6%

The complex of carbon monoxide and cuprous chloride produced by theaforedescribed process can be separated from the iron containing liquorsby filtration. The precipitate. the complex of carbon monoxide andcuprous chloride can be heated to drive off carbon monoxide and leavecuprous chloride according to the proposed equation The decomposition ofthe complex of cuprous chloride and carbon monoxide proceeds veryreadily at temperatures just above ambient and at atmospheric pressures,and. therefore, extreme conditions of temperature and pressure need notbe used. Thus, for example, at 25C. and at atmospheric pressure thecomplex of cuprous chloride and carbon monoxide will decompose tocuprous chloride in about two hours. By raising the temperature to 60C..while keeping the pressure at one atmosphere, the complex will decomposeto cuprous chloride and carbon monoxide in about thirty minutes.Although the decomposition proceeds quite readily at atmosphericpressures, super atmospheric pressure can be used. The carbon monoxidecan be recycled to produce more carbon monoxide and cuprous chloridecomplex according to the above described process.

The cuprous chloride obtained from the decomposition of the complex ofcarbon monoxide and cuprous chloride can be reduced by heating in thepresence of an appropriate reducing agent to give copper metal ofexceedingly high purity. Two methods of reducing copper chloride toproduce pure copper are heating the euprous chloride in the presence ofa reducing gas such as hydrogen, carbon monoxide. or synthesis gas, andheating the cuprous chloride in the presence of carbon and water.

According to the first method the copper chloride precipitate is heatedin the presence of a reducing gas at elevated temperatures to reduce thecopper chloride to copper metal. The process can be conducted underhydrogen or other reducing gas pressure. in other words, although it ispossible to conduct the process at atmospheric pressure. it is alsopossible to conduct the process at super-atmospheric pressure.Generally, better results are obtained when super-atmospheric pressuresof reducing gas are used. Preferably, the reducing gas pressure isgreater than psia. more preferably in the range of from about 200 toabout 1500 psia. There is no real upper limit on the reducing gaspressure; and accordingly the reducing gas pressure is not critical. Theupper pressure limit is restricted by such secondary considerations asdesign of the reaction vessel. economics. etc.

Likewise, the time of the reaction and the temperature at which thereduction is carried out are not critical. Generally, the temperaturesshould be above about 100C. Preferably the temperature is between l and650C. As with the pressure, the temperature at which the reaction iscarried out is not critical, but should be sufficient for the reactionto proceed at a reasonable rate. As a general rule the time of thereaction depends upon the factors of temperature and pressure. Thehigher the temperature the quicker the reduction. and conversely. thelower the temperature, the longer the time required for reduction of thecuprous chloride to copper metal.

In one example, a sample of cuprous chloride was reduced to copper metalwith hydrogen at atmospheric pressure by heating at about 400-440C. fortwo hours. The copper metal thus obtained was 99.9% pure.

When heating the copper chloride in the presence of carbon and water.pressures of about one atmosphere or higher can be used in conjunctionwith temperatures of about 650C. As with a reducing gas, the pressure isnot critical and is limited, at its upper limits, only by such secondaryconsiderations as design of the reaction vessel, economics, etc.

An advantageous process wherein the volatilization of unreacted cuprouschloride is reduced and which allows easier handling of the cuprouschloride material involves making pellets of cuprous chloride andcarbon. These pellets can vary in size from about 1/8 of an inch toabout 2 inches in diameter, with the most preferred size being about ofan inch. The cuprous chloride in these pellets is reduced to coppermetal by contacting the pellets with steam. Alternately, the pellets canbe contacted with a mixture of steam and carbon monoxide.

We claim:

l. A process for recovering copper metal from an acidic solutioncontaining copper ions, iron ions and chloride ions which comprises 1.treating said solution with a carbon monoxide containing gas at elevatedtemperatures and pressures for a time sufficient to form acopper-containing complex as a precipitate.

2. separating said precipitated complex from said solution,

3. heating said precipitated complex to obtain copper chloride, and

4. reducing said copper chloride. whereby copper metal of high purity isobtained.

2. A process of claim 1 wherein said solution is an aqueous solution.

3. A process of claim 2 wherein there is at least one gram ion ofchloride ion available for bonding with each gram atom of said copperions.

4. A process of claim 3 wherein said copper ions are in the cuprousvalence state.

S. A process of claim 3 being conducted under carbon monoxide pressureof from about I00 to about 1500 psia.

6. A process of claim I wherein the copper chloride is cuprous chloride.

7. A process of claim 6 wherein the cuprous chloride is reduced byheating in the presence of a reducing agent.

8. A process of claim 7 wherein the reducing agent is a gas selectedfrom the group consisting of hydrogen, carbon monoxide, or synthesisgas.

9. A process of claim 6 wherein the cuprous chloride is heated in thepresence of carbon and steam.

10, The process of claim 6 further including forming i pellets ofcuprous chloride and carbon.

1 l. The process of claim 10 wherein said pellets are treated withsteam.

12. The process of claim 10 wherein said pellets are exposed to amixture of steam and carbon monoxide.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTIONPATENTNO. 5,918,962

DATED November 11, 1975 |NVENTOR(S) Michael Dubeck et al It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 1, line W, "of" (second instance) should be or Column t, line 27,the equation "Cu Cl COOH OA Cu Cl C0 H O" should be Cu Cl CO'H O 011 01co H2O Signed and Scaled this sixteenth D3) 0f March 1976 [SEAL] Artest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner nfPalenrsand Trademarks

1. A PROCESS FOR RECOVERING COPPER METAL FROM AN ACIDIC SOLUTIONCONTAINING COPPER IONS, IRON IONS AND CHLORIDE IONS WHICH COMPRISES 1.TREATING SAID SOLUTION WITH A CARBON MONOXIDE CONTAINING GAS AT ELEVATEDTEMPERATURES AND PRESSURES FOR A TIME SUFFICIENT TO FORM ACOPPER-CONTAINING COMPLEX AS A PRECAPITATE,
 2. separating saidprecipitated complex from said solution,
 2. A process of claim 1 whereinsaid solution is an aqueous solution.
 2. SEPARATING SAID PRECIPITATEDCOMPLEX FROM SAID SOLUTION,
 3. HEATING SAID PRECIPITATED COMPLEX TOOBTAIN COPPER CHLORIDE, AND
 3. A process of claim 2 wherein there is atleast one gram ion of chloride ion available for bonding with each gramatom of said copper ions.
 3. heating said precipitated complex to obtaincopper chloride, and
 4. reducing said copper chloride, whereby coppermetal of high purity is obtained.
 4. A process of claim 3 wherein saidcopper ions are in the cuprous valence state.
 4. REDUCING SAID COPPERCHLORIDE, WHEREBY COPPER METAL OF HIGH PURITY IS OBTAINED.
 5. A processof claim 3 being conducted under carbon monoxide pressure of from about100 to about 1500 psia.
 6. A process of claim 1 wherein the copperchloride is cuprous chloride.
 7. A process of claim 6 wherein thecuprous chloride is reduced by heating in the presence of a reducingagent.
 8. A process of claim 7 wherein the reducing agent is a gasselected from the group consisting of hydrogen, carbon monoxide, orsynthesis gas.
 9. A process of claim 6 wherein the cuprous chloride isheated in the presence of carbon and steam.
 10. The process of claim 6further including forming pellets of cuprous chloride and carbon. 11.The process of claim 10 wherein said pellets are treated with steam. 12.The process of claim 10 wherein said pellets are exposed to a mixture ofsteam and carbon monoxide.